Reduced expression of N-Myc downstream-regulated gene 2 in human thyroid cancer.
BACKGROUND
NDRG2 (N-Myc downstream-regulated gene 2) was initially cloned in our laboratory. Previous results have shown that NDRG2 expressed differentially in normal and cancer tissues. Specifically, NDRG2 mRNA was down-regulated or undetectable in several human cancers, and over-expression of NDRG2 inhibited the proliferation of cancer cells. NDRG2 also exerts important functions in cell differentiation and tumor suppression. However, it remains unclear whether NDRG2 participates in carcinogenesis of the thyroid.


METHODS
In this study, we investigated the expression profile of human NDRG2 in thyroid adenomas and carcinomas, by examining tissues from individuals with thyroid adenomas (n = 40) and carcinomas (n = 35), along with corresponding normal tissues. Immunohistochemistry, quantitative RT-PCR and western blot methods were utilized to determine both the protein and mRNA expression status of Ndrg2 and c-Myc.


RESULTS
The immunostaining analysis revealed a decrease of Ndrg2 expression in thyroid carcinomas. When comparing adenomas or carcinomas with adjacent normal tissue from the same individual, the mRNA expression level of NDRG2 was significantly decreased in thyroid carcinoma tissues, while there was little difference in adenoma tissues. This differential expression was confirmed at the protein level by western blotting. However, there were no significant correlations of NDRG2 expression with gender, age, different histotypes of thyroid cancers or distant metastases.


CONCLUSIONS
Our data indicates that NDRG2 may participate in thyroid carcinogenesis. This finding provides novel insight into the important role of NDRG2 in the development of thyroid carcinomas. Future studies are needed to address whether the down-regulation of NDRG2 is a cause or a consequence of the progression from a normal thyroid to a carcinoma.
Zhao
Huadong
H
Department of General Surgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710038, PR China. zhaolujy@fmmu.edu.cn
Zhang
Jian
J
Lu
Jianguo
J
He
Xianli
X
Chen
Changsheng
C
Li
Xiaojun
X
Gong
Li
L
Bao
Guoqiang
G
Fu
Qiang
Q
Chen
Suning
S
Lin
Wei
W
Shi
Hai
H
Ma
Jianjun
J
Liu
Xinping
X
Ma
Qingjiu
Q
Yao
Libo
L
D000236:Adenoma / Q000235:genetics* / Q000473:pathology; D000328:Adult; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis; D008297:Male; D046228:Microarray Analysis; D008875:Middle Aged; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000032:analysis; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
C466228:NDRG2 protein, human; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins